Conventionally, Patent Document 1 discloses a vapor compression type refrigeration cycle device configured to be capable of switching between a refrigerant circuit in a heating mode, which heats ventilation air as a heat exchange target fluid to perform heating of an air conditioning target space, and a refrigerant circuit in a cooling mode which cools ventilation air to perform cooling of the air conditioning target space.
In addition, the refrigeration cycle device of Patent Document 1 forms a gas injection cycle (economizer type refrigeration cycle) which joins an intermediate-pressure gas phase refrigerant in the cycle to a refrigerant in a compression process by a compressor even when a refrigerant circuit of any one operation mode of the heating and cooling modes is switched. Accordingly, the refrigeration cycle device of Patent Document 1 improves compression efficiency of the compressor in both operation modes so as to enhance a coefficient of performance (COP) of the refrigeration cycle device.
Meanwhile, as a cycle configuration aimed to enhance a COP of a refrigeration cycle device, there has been known an ejector type refrigeration cycle adapting an ejector as a refrigerant pressure reducer as disclosed in Patent Document 2, besides the gas injection cycle. Such an ejector type refrigeration cycle absorbs a refrigerant flowing out of an evaporator by absorption action of an injection refrigerant injected from a nozzle section of the ejector so as to recover a loss of kinetic energy caused when the refrigerant is decompressed by the nozzle section.
Then, the recovered kinetic energy and kinetic energy of the injection refrigerant are converted into pressure energy by a diffuser section of the ejector. Accordingly, in the ejector type refrigeration cycle, since a suction-side refrigerant pressure of a compressor may be increased, driving power of the compressor is reduced compared to a typical refrigeration cycle device having an expansion valve. Consequently, a COP of the ejector type refrigeration cycle is enhanced.